Hydraulic trim device, boat drive and boat

ABSTRACT

A hydraulic trim device is provided for a boat motor with at least one trimming cylinder, a piston rod movable axially in the trimming cylinder between a first end position and a second end position, a trimming plate and a hydraulic unit. The trimming cylinder can be pressurized via the hydraulic unit to extend the piston rod. The piston rod has a contact portion and the trimming plate has an contact surface and the contact portion is in contact with the contact surface. The contact portion moves along the contact surface when the piston rod moves between the first end position and the second end position relative to the contact surface. The contact surface at least partially has a convex curvature in the direction of the piston rod. A boat motor with a hydraulic trim device and to a boat with such a boat motor are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German patent application 10 2021 213 912.4, filed Dec. 7, 2021, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a hydraulic trim device for a boat motor, a boat motor comprising such a trim device, and a boat comprising such a boat motor. Such boat motors regularly comprise a boat drive, for example an outboard motor or a stern drive. The boat drive is pivotably arranged on the hull of the boat by means of the trim device.

BACKGROUND OF THE INVENTION

Such hydraulic trim devices for boat motors are known from the prior art, for example from U.S. Pat. No. 5,597,333 A or WO 01/98142 A. Usually, these hydraulic trim systems are used in combination with a hydraulic lift device. These combined devices are used on the one hand to pivot the boat drive, for example an outboard motor, via at least one lift cylinder of the lift device into a rest position in which the propeller of the drive is almost completely or fully lifted out of the water.

Further, at least one trimming cylinder of the trim device is used to perform a so-called power trim while the boat is travelling. Here, the boat drive is finely adjusted by rotation around the transverse axis of the boat in order to obtain an optimum alignment or position of the hull of the boat with respect to the water surface during travel. A suboptimal alignment between the hull and the water surface results in a loss of propulsion due to cavitation of the propeller as well as incorrect power input direction, unsteady handling and increased fuel consumption.

For this purpose, the hydraulic trim device has, in addition to the at least one trimming cylinder, a hydraulic unit and a trimming plate. The trimming cylinder comprises a piston rod axially movable in the trimming cylinder between a first end position and a second end position. In sense of the present invention, the first end position may correspond to a minimum trim position, which position may also correspond to the fully retracted position of the piston rod. The second end position may correspond to a maximum trim position, whereby this may correspond to a fully extended position of the piston rod. To extend the piston rod in the direction of the second end position, the trimming cylinder is pressurized in a known manner via the hydraulic unit.

The piston rod has a contact portion which is in contact with a contact surface of the trimming plate. The trimming plate is disposed on the boat drive so that the boat drive is pivoted relative to the hull by extending and retracting the piston rod. When the piston rod moves between the first end position and the second end position, the contact portion moves relative to the contact surface along the contact surface.

In known trim devices, the movement between the contact portion and the contact surface can result in transverse forces that increase wear, for example on guide bushings of the trimming cylinder. In particular, the friction between the contact portion and the contact surface also causes the piston rod to stop and move alternately, which is also noticeable in the form of vibrations. This phenomenon is also referred to as the slip-stick effect. As a result, there is also an undesirable noise formation, which manifests itself as a kind of rattling. As a general remedy, it is suggested that the contact surface or contact portion be lubricated regularly, which also has a positive effect on the wear between the contact surface and contact portion.

In addition, U.S. Pat. No. 5,597,333 A suggests that the trimming plate may be in the nature of a ball bearing, or that the contact surface may be symmetrically concavely curved, i.e., curved inward away from the contact portion.

The disadvantage of this is that the solution in the form of a ball bearing is very complex and therefore expensive to manufacture. The solution with concavely curved contact surfaces also only works satisfactorily with regular application of lubricant, whereby the transverse forces are even higher, depending on the position of the piston rod, than with a completely flat contact surface. Increased use of lubricant is also undesirable for ecological reasons, as a considerable proportion of the lubricant is discharged into the waterways due to its aquatic use in boat motors.

SUMMARY OF THE INVENTION

It is therefore the object of the present invention to provide a hydraulic trim device for a boat motor, with which the undesirable transverse forces as well as the undesirable noise development can be effectively prevented with reduced use of lubricant. The solution of the problem is achieved with a hydraulic trim device as disclosed herein. Preferable embodiments are also described.

The hydraulic trim device according to the invention is characterized over the trim devices known in the prior art in that the contact surface at least partially has a convex curvature in the direction of the piston rod. In other words, the contact surface at least partially curved outwardly in the direction of the piston rod or the contact portion. In this way, it can be ensured that the transverse force is significantly minimized, whereby the use of lubricant can also be noticeably reduced. Tests by the applicant have shown that, compared with conventional trim devices with flat contact surfaces, up to five times the number of movements can be achieved with the same use of lubricant.

Preferably, the contact portion is in a first contact position in the first end position of the piston rod and in a second contact position in the second end position of the piston rod. Preferably, the convex curvature of the contact surface between the first contact position and the second contact position is asymmetrical. In other words, the trimming plate is thus symmetrical along a first imaginary plane between the first end position and the second end position, but asymmetrical along a second plane perpendicular to the first plane. Thus, the trimming plate can be individually matched to the corresponding kinematics of the boat drive with respect to trim or power trim.

Preferably, the contact surface between the first contact position and the second contact position has a completely convex curvature in the direction of the piston rod. This means that the contact surface is not only convexly curved partially or in sections, but completely.

Preferably, the piston rod has a central mid-axis, the convex curvature of the contact surface being such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is orthogonal on the trimming plate or contact surface or is inclined by at most 6° on the trimming plate or contact surface. If the central mid-axis of the piston rod is inclined on the trimming plate or the contact surface, it is useful if the central mid-axis is inclined between 1.5° and 4.5°, preferably by 2° to 4° and particularly preferably by 3° on the trimming plate or the contact surface. A completely orthogonal arrangement results in the lowest transverse forces and consequently the lowest wear. With a certain inclination, the slip-stick effect can be largely suppressed, with tests by the applicant showing that the best compromise between reduced transverse forces and reduced slip-stick effect can be achieved at an inclination of 3°.

Preferably, the central mid-axis is inclined in the direction of the first contact position. By inclining the central mid-axis in the direction of the first contact position, the slip-stick effect is noticeably reduced, especially when the piston rod is extended.

Preferably, the contact portion is a spherical contact portion. This results in point contact between the contact portion and the contact surface. Alternatively, the contact portion can be a planar contact portion. This results in a line contact, which reduces the surface pressure. Furthermore, a flat contact portion is easy to manufacture. Of course, other shapes of the contact portion are also conceivable, for example semi-cylindrical, partially cylindrical or frustoconical.

Furthermore, the solution of the problem is achieved with a boat motor disclosed herein. According to the invention, the boat motor comprises a trim device described above as well as a boat drive. The trimming plate is attached to the boat drive. The boat drive may in particular be an outboard motor or a stern drive.

Furthermore, the solution of the task succeeds with a boat, in particular a sports boat. The boat according to the invention has a hull and a boat motor described above, the boat drive being pivotably arranged on the hull by means of the hydraulic trim device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is explained in more detail with reference to exemplary embodiments shown in the figures. The figures show schematically:

FIG. 1 is a first side view of a boat with an outboard motor;

FIG. 2 is a second side view of the boat shown in FIG. 1 ;

FIG. 3 is a side view of a hydraulic trim device according to a first embodiment with a trimming cylinder and a piston rod located in a first end position;

FIG. 4 is a side view of the hydraulic trim device shown in FIG. 3 with the piston rod in an intermediate position;

FIG. 5 is a side view of the hydraulic trim device shown in FIG. 3 with the piston rod in a second end position;

FIG. 6 is a detail view of the hydraulic trim device shown in FIG. 3 ; and

FIG. 7 is a side view of a hydraulic trim device according to a second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2 , a boat 101 with a boat motor 100 according to the invention is shown. In this embodiment, the boat is a recreational boat and the boat motor 100 has a boat drive in the form of an outboard motor 105. In a known manner, the outboard motor 105 comprises a propeller 104 and is pivotable on a hull 102 of the boat 101 via a joint 103 between a lowered position (see FIG. 1 ) and a raised position (see FIG. 2 ). For this purpose, the boat 101 has a hydraulic trim device 1 according to the invention as part of a combined hydraulic trim-lift device 110.

The hydraulic trim lift device 110 has a lift cylinder 106 and, in this embodiment, a trimming cylinder 2 as part of the hydraulic trim device 1. Of course, embodiments with two or more lift cylinders and with two or more trimming cylinders are also conceivable. Furthermore, a hydraulic unit (not shown in more detail) is provided, via which the lift cylinder 106 and the trimming cylinder 2 can be pressurized in a known manner.

The trimming cylinder 2 has a piston rod 3 which can be moved axially between a first end position EP1 and a second end position EP2 in the trimming cylinder 2, see also FIGS. 3 to 5 . By pressurizing the trimming cylinder 2 via the hydraulic unit, the piston rod 3 is extended in the conventional manner. A contact portion 4, 4′ is provided at the axial end of the piston rod 3 facing a trimming plate 5 being disposed on the outboard motor 105. The contact portion 4, 4′ is in contact with a contact surface 6 of the trimming plate 5.

During power trimming while the boat 101 is travelling, the trimming cylinder 2 extends and the contact portion 4, 4′ of the piston rod 3 of the trimming cylinder 2 moves along the contact surface 6 of the trimming plate 5 to pivot the outboard motor 105 relative to the hull 102 along the joint 103 about the transverse axis of the boat 101 to fine-tune between the lowered position (FIG. 1 ) and raised position (FIG. 2 ). Suboptimal alignment between the hull 102 and the water surface results in a loss of propulsion due to cavitation of the propeller 104 as well as incorrect force application direction, erratic handling and increased fuel consumption.

In FIG. 3 , a hydraulic trim device 1 is shown as part of a combined hydraulic trim-lift device 110 according to a first embodiment. The outboard motor 105 is not shown for clarity reasons. The state shown in FIG. 3 corresponds essentially to the state shown in FIG. 1 with the outboard motor 105 fully lowered and therefore not finely adjusted. The piston rod 3 of the trimming cylinder 2 is in the first end position EP1 and the contact portion 4 of the piston rod 3 is in a first contact position AP1 on the contact surface 6 of the trimming plate 5.

In this embodiment, the contact portion 4 of the piston rod 3 is spherical, so that there is point contact between the contact portion 4 and the contact surface 6. As shown, the contact surface 6 of the trimming plate 5 has a convex curvature in the direction of the piston rod 3 or the contact portion 4, as will be described in more detail below.

To perform a power trim, the trimming cylinder 2 is pressurized by the hydraulic unit in the conventional manner and the piston rod 3 extends. Here, the contact portion 4 of the piston rod 3 moves along the contact surface 6 of the trimming plate 5 and a force is applied to the outboard motor 105 via the trimming plate 5 so that the outboard motor 105 is moved or pivoted relative to the hull 102 via the joint 103.

FIG. 4 shows an intermediate position of the contact portion 4 of the piston rod 3 on the contact surface 6 of the trimming plate 5, and FIG. 5 shows a state essentially corresponding to the state shown in FIG. 2 , which corresponds to maximum power trim. In the state shown in FIG. 5 , the piston rod 3 is in the second end position EP2 and the contact portion 4 of the piston rod 3 is in a second contact position AP2 on the contact surface 6 of the trimming plate 5.

FIG. 6 shows a detail from FIG. 3 , in which the contact portion 4 of the piston rod 3 is located in the first contact position AP1 on the contact surface 6 of the trimming plate 5. The piston rod 3 has a central mid-axis MA. The curvature of the contact surface 6 of the trimming plate 5 is selected such that the central mid-axis MA is always inclined by a predetermined angle α relative to the force introduction direction KE shown as a dashed arrow during movement along the contact surface 6 between the first contact position AP1 and the second contact position AP2. In this exemplary embodiment, α=3°. In other words, the piston rod 3 is not orthogonal on the contact surface 6 of the trimming plate 5, but the central mid-axis MA is inclined in the direction of the first contact position AP by the angle α=3° with respect to the force introduction direction KE. The contact surface 6 or the curvature of the contact surface 6 respectively is configured so that the angle α remains the same for all positions of the contact portion 4 relative to the contact surface 7.

If the central mid-axis MA of the piston rod 3 were completely orthogonal relative to the trimming plate 5 or contact surface 6, α=0° and MA=KE would apply. In this case, the lateral forces would be minimal due to the orthogonal force application, but a noticeable slip-stick effect could occur. It has been shown that with α≤6° and especially in the range of 1.5°≤α≤4.5° an optimum compromise between introduced transverse forces and occurrence of the slip-stick effect can be achieved.

When configuring the curvature of the contact surface 6 of the trimming plate 5, this is initially selected so that it is individually matched to the corresponding kinematics of the boat motor 100 with regard to trim or power trim. Here, it is notionally assumed that an orthogonal alignment of the central mid-axis MA of the piston rod 3 to the trimming plate 5 or contact surface 6 is always to be achieved. Subsequently, if required, the contact surface 6 of the trimming plate 5 is rotated by an angle α, the angle α being at most 6°. This results in an asymmetrical and convex curvature of the contact surface 6 of the trimming plate 5 between the first contact position AP1 and the second contact position AP2.

In FIG. 7 , a hydraulic trim device 1 is shown as part of a combined hydraulic trim-lift device 110 according to a second embodiment. The second embodiment of the hydraulic trim device 1 differs from the first embodiment shown in FIGS. 3 to 6 only in the design of the contact portion 4′ of the piston rod 3.

As shown, the contact portion 4′ of the piston rod 3 in this second embodiment is designed as a flat surface. Thus, in contrast to the spherical design of the contact portion according to the first embodiment, there is a line contact between the contact portion 4′ of the piston rod 3 and the contact surface 6 of the trimming plate 5. In this embodiment, the angle α=0°. Overall, this results in lower surface pressure with minimized slip-stick effect.

LIST OF REFERENCE SIGNS

-   1 hydraulic trim device -   2 trimming cylinder -   3 piston rod -   4, 4′ contact portion -   5 trimming plate -   6 contact surface -   100 boat motor -   101 boat -   102 hull -   103 joint -   104 propeller -   105 boat drive -   106 lift cylinder -   110 hydraulic trim-lift device -   AP1 first contact position -   AP2 second contact position -   EP1 first end position -   EP2 second end position -   KE force introduction direction -   MA central mid-axis -   α angle 

1. A hydraulic trim device for a boat motor, comprising: at least one trimming cylinder; a piston rod movable axially in the trimming cylinder between a first end position and a second end position; a trimming plate; and a hydraulic unit; wherein; the trimming cylinder is pressurized via the hydraulic unit to extend the piston rod; the piston rod has a contact portion and the trimming plate has a contact surface, the contact portion being in contact with the contact surface; the contact portion moves along the contact surface during a movement of the piston rod between the first end position and the second end position relative to the contact surface; and the contact surface at least partially has a convex curvature in a direction of the piston rod.
 2. The hydraulic trim device according to claim 1, wherein the contact portion is in a first contact position in the first end position of the piston rod and in a second contact position in the second end position of the piston rod, the convex curvature of the contact surface between the first contact position and the second contact position being asymmetrical.
 3. The hydraulic trim device according to claim 1, wherein the piston rod has a central mid-axis, the convex curvature being such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is orthogonal on the trimming plate.
 4. The hydraulic trim device according to claim 1, wherein the piston rod has a central mid-axis, the convex curvature being such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is inclined by at most 6° on the trimming plate.
 5. The hydraulic trim device according to claim 4, wherein the central mid-axis of the piston rod is inclined on the trimming plate by between 1.5° and 4.5°, or by 2° to 4° and or by 3°.
 6. The hydraulic trim device according to claim 4, wherein the central mid-axis of the piston rod is inclined in a direction of the first contact position.
 7. The hydraulic trim device according to claim 1, wherein the contact portion is a spherical contact portion.
 8. The hydraulic trim device according to claim 1, wherein the contact portion is a planar contact portion.
 9. A boat motor comprising: a boat drive; and a hydraulic trim device according to claim 1; wherein the trimming plate is disposed on the boat drive.
 10. A boat comprising: a hull; and a boat motor according to claim 9; wherein the boat drive is pivotably arranged on the hull by the hydraulic trim device.
 11. The boat according to claim 10, wherein the boat is a sports boat. 